Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view of the first image in the first embodiment of a display screen or portion thereof with transitional graphical user interface showing our new design;

FIG. 2 is a second image thereof;

FIG. 3 is a third image thereof;

FIG. 4 is a fourth image thereof;

FIG. 5 is a fifth image thereof;

FIG. 6 is a front view of the first image in the second embodiment of a display screen or portion thereof with transitional graphical user interface;

FIG. 7 is a second image thereof;

FIG. 8 is a third image thereof;

FIG. 9 is a fourth image thereof; and,

FIG. 10 is a fifth image thereof.

The broken lines in the figures depict environmental subject matter and form no part of the claimed design.

The outermost broken line in the figures shows a display screen or portion thereof and forms no part of the claimed design.

The appearance of the transitional graphical user interface sequentially transitions between the images shown in FIGS. 1-5 and FIGS. 6-10. The process or period in which one image transitions to another forms no part of the claimed design. 

CLAIM We claim the ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 